Start Date: Sep 13, 2013
End Date: Sep 12, 2018
The approach uses the ECa-directed soil sampling protocols developed by Corwin and Lesch (2003, 2005, 2013) and the stream-tube approach of Corwin et al. (1999) as a basis for delineating stream tubes used in the spatial parameterization of field-scale functional and mechanistic solute transport models. Preliminary stream tubes were defined in 2014 using the geometric mean and ratio of horizontal and vertical coil configuration measurements with the Geonics EM38. Randomly selected sites within each stream tube were chosen for parameterization. Evaluation of the preliminary stream tubes indicated that the high level of spatial variability both vertically and horizontally required a more sophisticated means of defining stream tubes beyond the approach of Corwin et al. (1999). Subsequently, inverse modeling of ECa measurements with the Dualem-421s electromagnetic sensor, which provides six simultaneous depths of ECa sounding, will be added to the original approach to define in greater detail the conductivity profile and thereby refine the delineation of stream tubes. Once newly defined stream tubes are obtained, physical and chemical solute transport model parameters will be determined for a selected solute transport model (i.e., UNSATCHEM or TETrans) at selected sites within each stream tube. This amendment to the original agreement specifically entails the delineation of stream tubes using the addition of 3-D maps of ECa obtained from inverse modeling of Dualem-421s data and the analysis of model parameters for the newly defined stream tubes.